Process of shrinking nylon fabrics with mixtures of specific chemical shrinking agents



Jan. 11, 1966 c. GALATloTo 3,228,745 RIcs WITH MIXTURES 0F SPECIFICPROCESS OF SHRINKING NYLON FAB CHEMICAL SHRINKING AGENTS 8 Sheets-Sheetl Filed Jan. 10, 1961 Jan. 11, 1966 L. C. GALATIOTO PROCESS OF SHRINKINGNYLON FABRICS WITH MIXTURES OF SPECIFIC CHEMICAL SHRINKING AGENTS 8Sheets-Sheet 2 Filed Jan. lO, 1961 @SEER Qm z EQ im Jan. 11, 1966 L.. c.GALA-NOTO PROCESS OF SHRINKING NYLON FABRICS WITH MIXTURES OF SPECIFICCHEMICAL SHRINKING AGENTS 8 Sheets-Sheet 5 Filed Jan. lO. 1961 Jan. 11,1966 l.. c. GALATIOTO 3,228,745

PROCESS OF SHRINKING NYLON FABRICS WITH MIXTURES OF SPECIFIC CHEMICALSHRINKING AGENTS Filed Jan. lO, 1961 8 Sheets-Sheet 4 INVENTOR. Jaaa? lazzz'oi i Jan. 11, 1966 c. GALATloTo 3,228,745

H MIXTURES OF SPECIFIC PROCESS OF SHRINKING NYLON FABRICS WIT CHEMICALSHRINKING AGENTS 8 Sheets-Sheet 5 Filed Jan. l0 1961 INVENz'oR. [0025 6.alzz'vza Jan. 11, 1966 1 c. GALATloTo 3,228,745

PROCESS OF SHRINKING NYLON FABRICS WITH MIXTURES OF SPECIFIC CHEMICALSHRINKING AGENTS Filed Jan. 10, 1961 8 Sheets-Sheet 6 Jan. l1, 1966 l..c. GALATloTo PROCESS OF SHRINKING NYLON FABRICS WITH MIXTURES OFSPECIFIC CHEMICAL SHRINKING AGENTS Filed Jan. l0, 1961 8 Sheets-Sheet 7S QN uw S S qm ww uw S uw 9 Q ESS@ SQMS Q QW wv UQW MMLSQU Jan. l1, 19661 c. GALATlo-ro ON FABRICS WITH MIXTURES OF SPECIFIC PROCESS OFSHRINKING NYL CHEMICAL SHRINKING AGENTS 8 Sheets-Sheet 8 Filed Jan. lO,1961 QSQ u@ knuhvgk INVENToR. Jada@ 6. alzz'oza United States Patent C)3,228,745 PROCESS OF SHRINKING NYLON FABRICS WITH MIXTURES F SPECIFICCHEMICAL SHRINK- ING AGENTS Louis C. Galatioto, Roseto, Pa., assgnor, hymesne assignments, to Lehigh Valley Industries Inc., New York, N.Y., acorporation of Delaware Filed Jan. 10, 1961, Ser. No. 81,874 1 Claim.(Cl. 8-130.1)

The present invention relates to a method of treating certain synthetictextile materials, such as filaments, fibers, yarns and threads, moreespecially in knitted form 0r woven condition, characteristically toshrink the same, and to the resulting products.

It is a fundamental, characteristic property of all synthetic filaments,fibers, yarns or threads, and hence of fabricated textile or otherproducts made from themthat their surfaces are relatively physically andchemically resistant, continuous, smooth and hard--and hence nonfeltinginter se, and of low frictional propensities, if any, with respect tothemselves and to other surfaces and materials, tending to give them aslick feel and a loose, free hand.

These properties are well known and recognized as being very valuablefeatures of such synthetic textile materials, for many purposes.However, it is sometimes desirable that they should have supplementaryproperties and characteristics which would render them applicable oradaptable to further uses, functions and conditions, which, in theirusual state of manufacture and use, they are quite incapable of serving.

Thus, if an open or looser weave or structure is desired, this can beprovided in the original spinning, twisting, weaving or knittingoperations or even in the finished goods, by tensioning.

But if a very firm, compact Weave or structure is to be desired, thismay not be so readily provided in the originally spun yarns or in thetwisted threads, nor in the woven or knitted goods made from them. And,insofar as it can be and is effected, the original spun structure of theyarn and twisted structure of the threads and woven or knitted weave orstructure of the goods may, each and all, be subject to appreciabledegrees of reduction (and consequent warping) in the course of the usualwinding, handling and storing of the goods themselves and before orduring or after use, for the ultimate purposes which they are intendedto serve.

Accordingly, it is an object of the present invention to provide amethod of treating synthetic filaments, fibers, yarns, threads, andwoven, knitted or otherwise fabricated textile materials or goods madefrom them, which are characteristically relatively physically andchemically resistant, partially water-repellent, and of continuous,hard, smooth surfaces, whereby these inherent tendencies to lose theirfirm, compact structure of spinning, twisting, weaving, knitting orother type of fabrication tending to integrate them, may be checked; or,more particularly, whereby the firm, compact structure of the spunyarns, twisted threads, woven or knitted or otherwise fabricated textilematerials or goods, may be positively enhanced and preserved throughoutthe normal courses of their manufacture, handling, storage and theintermediate or ultimate uses to which they are to be put.

Briefly, it is an object of the invention to effect the positive,uniform, controlled shrinkage of such materials in length and/orcross-section of filaments, fibers, yarns, or threads, in length and/ orwidth of woven goods and Wale-wise and/or course-wise of knitted goods,to the degree desired.

ICC

Other objects will appear from the following disclosures anddescriptions of the invention and from the claim.

By the present invention, it has been discovered that the more stable,chemically and physically resistant, synthetic filaments, fibers, yarnsand threads, and knitted, woven or otherwise fabricated textile goodsmade from them, such as nylon which is a generic term for any long chainsynthetic polymeric amide, having recurring amide groups as an integralpart -of the polymer amide chain, and which is capable of being formedinto a lilament in which the structural elements are oriented in thedirection of the axis:

cellulose tri-acetate; and the like, may be given a feltingcharacteristic or function, and consequently a shrinking action, wherebythe filament, yarn, liber or thread, or fabricated textiles made from orcontaining it, may be felted and/or shrunk, to substantially any desireddegree or effect, uniformly throughout their dimensions or surfaces, orselectively in this respect, and without deleterious action thereon butimprovements in other respects, such as feel, hand, strength,susceptibility to dyes and dyeing, and the like.

It is well known that such synthetic, chemically resistant filaments,fibers, yarns, threads, and the various products made from them, aresensitive to some solvents, which may be active enough, under sufficientconditions of concentration, temperature and time, to dissolve them. Inthe course of such action, the solvent penetrates first the superficialsurfaces of the product and then progressively into an ultimatelythroughout its structure, reducing it to a dispersed condition or to aliquid solution.

It is also well known that such synthetic, chemically and physicallyresistant filaments, fibers, threads, and the various textile productsmade from them, are sensitive to other reagent liquids, which penetratethe superficial surfaces, under sufficient conditions of concentration,temperature and time. They are not dissolved by such reagents but tendto gelatinize. In the course of such action, the superficial surfacestreated swell and subsequently the body structure of the filament,fiber, yarn or thread, or of the goods treated, as a whole. But theintegrity and general shape and solid characteristics, generally aremaintained.

It is found by the present invention that by treating chemically andphysically resistant synthetic filaments, fibers, yarns, threads, andwoven, knitted or otherwise formed textile goods, with an aqueoussolution containing a solvent of the same in a concentration sufficientpartially to dissolve the surface and/or with an aqueous solutioncontaining a gelatiniz'ing agent, in sufficient concentration partiallyto effect gelatinization of the surface, at a temperature not above theboiling point of the solution and for a time to control the action ofthe same, the thus treated surfaces acquire the characteristicproperties of felting and can be given substantially any degree ofshrinkage that may be desired and that it can be controlled andregulated, not only by the concentrations and conditions of the treatingsolution but definitively by the removal of the treating solution fromthe treated surface and subsequent neutralization and stabilization.

It is believed that the shrinking action thus produced is a composite ofthe dispersing or dissolving action of the solvent upon the treatedsurface and of the opposite of restraining action or contractingtendency of the gelatinizing agent upon the thus partially dissolved,relaxed or dispersed superficial surface or surfaces. These opposedforces result in a fine wrinkling or folding of the superficial surfaceareas which, -upon removal of the solution, are capable of manifesting atypical felting action between such surfaces, per se, and also withother similar surfaces, with a consequent shrinking action upon thefilaments, fibers, yarns, threads, individually, and also between themand others in the woven, knitted or otherwise fabricated textile goodswhich they may constitute or of which they may form a part.

In accordance with the present invention, it may be said that the actionof the solvent reagents upon the surlfaces of the goods, when applied,per se, is more rapid and more drastic than the action of thegelatinizing agents, per se. Moreover, at high concentrations, at hightemperatures and for prolonged periods of treatment, the solvents willnot only wet, attack and soften, but ultimately disperse or dissolve thesurface or even the entire body structure of the filament. Thegelatinizing agents Will also attack and soften lthe surfaces andstructure of the filament. On the other hand the gelatinizing agentswill not disperse nor dissolve the surface but will cause it to swelland gelatinize and at the same time leave it in its original shape andgeneral conformation-though swollen in its dimensions and hencesusceptible to distortion and to folding or wrinkling, superficially.

Both reagents, when applied in the higher ranges of concentration or athigher temperatures or for prolonged periods of time, Will soften thesurfaces of the chemically and physically resistant synthetic filamentsand textile goods made from them, and, as a result will render themsusceptible to appreciable shrinkage. It would therefore be possible,within the present invention, to shrink such filaments or the goods madefrom them, by treating with concentrated solvent reagents orconcentrated gelatinizing agents, severally or successively, at lowtemperatures or even at high temperatures, if suitably confined so as toavoid fuming into the atmosphere and checked in respect of their actionsupon the goods, as by prompt removalsuch as vaporization, cooling,neutralization or dilution with an inert solvent, such as water or thelike. But such actions and reactions are apt to be too rapid, thereagents subject to vaporization and escape or develop in too short atime for effective or convenient control. It is therefore generallydesirable that the reagents be reduced in concentration, with an inertsolvent, such as water.

Thus, a practical limitation applies to the concentration of the solventreagent and of the gelatinizing reagent, or mitxure of them. As ageneral rule, the active reagent or total of active agents used willnever be above 90% by volume of the treating solution. Suchconcentrations, being very high, Would make the resultingreagentsolutions very active, Very expensive and very difficult tohandle in operation, as above pointed out. As a matter of practice,therefore, lower concentrations will ordinarily be preferred and used.Accordingly, an upper limit of 75%, more or less, is both safer and lessexpensive and in fact an upper limit, from the standpoint of efficiency,economy and convenience, will usually be adopted in commercialoperations and practice. On the other hand the treating solution shouldcontain at least about by volume, of the solvent reagent or gelatinizingreagent, or both, in order to effect a shrinkage of 16% or greater (inone direction or the other, or the sum of the two), and hence the inertsolvent or diluent component of the solution, such as water,inassociation therewith, will not 'exceed about 75%, more or less.

Some latitude, either way, in respect of these limitations, in terms ofconcentration of the reagents is therefore permissible and will benecessary and/or desirable. Moreover, their selection will be governedor modified by the temperature and time of treatment, as above pointedout, with added precautions accordingly to suit the exigencies of anyspecific case or condition of operation. These will include, to someextent, the appurtenant type and character of the apparatus available,and of course the material to be treated and the effects and resultsdesired to be accomplished therewith. But, in general, the usualequipment, means and apparatus for the handling of textiles, in Whateverstage of fabrication the material to be treated may be, will ordinarilybe sufficient and satisfactory for carrying out the present inventiontherein in order to effect the desired shrinking action and results, ifmade of a material sufficiently resistant to the acids, such as a goodgrade of stainless steel, wood, or plastics.

In general, of course, efiicient means and apparatus for rapid anduniform handling, wetting out, treating, treatments, concentrations,temperature and time controls, and removal of reagent solutions, as byneutralization, washing or the like, squeeze rolls, etc., will all bebeneficial, in their respective applications and effects on thefunctions, operations and results to be produced.

The solvent reagents, as above referred to, for the purposes of thepresent invention are: formic acid at 80 F. and above, phenoliccompounds such as carbolic acid, cresols, xylenols and chlorinatedphenols, calcium chloride in methanol (saturated solution at 80 F.), hotsolutions of calcium chloride in glacial acetic acid, ethylenechlorhydrin and ethylene glycol, hot solutions of zinc chloride inmethanol and benzyl alcohol at the boil. All dissolve nylon.

Mineral acids, such as sulphuric and hydrochloric, in lowconcentrations, cause loss in strength of nylon yarn and in higherconcentrations completely dissolve nylon.

The gelatinizing reagents, as above referred to, for the purposes ofthis invention are: acetic acid, adipic acid, aniline, benzene sulphonicacid, benzoic acid, boric acid, chloral hydrate, chloro-acetic acid,formic acid diluted, glycol, lactic acid, lithium bromide, metacresol,parahydroXybenZoic acid, phenol (e.g. 2% in H2O), phosphoric acid andzinc chloride. All cause nylon to swell or gelatinize.

It will be noticed that formic acid appears in both categories, that isto say, above 80 F. and in the more concentrated solutions containingformic acid it acts as a solvent, or dispersing reagent, while at lowertemperatures and in solutions of lower concentrations its activities arethose of gelatinizing or swelling reagents.

The mineral or inorganic acids, sulphuric and hydrochloric, while activesolvent reagents upon nylon are so much more so, even in lowconcentrations and at low temperatures, that they may more especially beregarded as catalysts of the solvent action of the organic solventreagents and also as imparting increased acidity or lower pH values tothe solutions to which they are added, even when in small amounts orrelative proportions.

For example, all of the reagent solutions which are found to besufiiciently active in the shrinking of the synthetic filaments, etc.,and products made from them, are highly acidic and manifest a pH valueof "1, or below l, and usually and preferentially a pH value below 'land even of `0 and below 0. The pH values of such solutions,accordingly, are negative, such as -1, -2, etc. This means, as apractical matter, that these solutions, upon dilution with water, havetheir pH values gradually raised thereby from their negative values toless negative values, Ithen to 0 and -then t-o a positive pH value above0 and between y0 and 1, in concentrations of the order of thosesolutions used in this invention. Such pH values, -therefore, of theorders of 1 to 0 and from 0 to -1, 2, etc., are to be considered asrepresenting the range of `acidity of -the reagent solutions which aresatisfactory for use in the present process of shrinking syntheticfilaments and the textile and like products made from them.

Example 1 A preliminary example of the invention was carried out with asolution of 25% (of 90%) formic acid and 75% water and applied tosw-atches of 40 denier nylon tricot knitted fabric at F., 120 F., and150 P. for

30 minutes, rinsed, neutralized with sodium bicarbonate and dried, withthe following results:

Shrinkage wales-wise percent 7 13 Shrinkage course-wise do 8 Example 2While the shrinkage in Example 1, with formic acid, Was barely sucientto be regarded as commercially sat-isfactory, especially at the lowertemperatures, it was promising and that obtained in Example 2 was highlysatisfactory and sutiicient for many purposes.

Example 3 On account of the high cost and consequent expense of usingformic acid in higher concentrations and the operation difcultiesinvolved in using high temperatures, tending to render the atmosphereirritating to the operators if not properly conned, i-t was then triedto replace a part of the formic acid or acetic acid with sulphuric acid.To this end an experiment was made with a solution containing 30% offormic acid (90%) and 30% of sulphuric acid Baume). Four swatches of thesame material were used. One was treated with plain water at y140 F. for20 minutes; as a control. The second was treated for y20 minutes at '90F. The third was treate-d for 20 minutes at 120 F. The fourth wastreated for 20 minutes at 140 F. They were t-hen rinsed, neutralized anddried, as before.

All swatches were observed for shrinkage and appearance. Except for thecontrol, or rst sample, they all Ishowed a marked increase in swellingas compared to the results obtained with formic acid (90%) alone, as inExample l.

The shrinkages obtained were the following:

Control Wales-wise 1%, course-wise 5%. Second Wales-Wise 13%,course-wise 13%. Third Wales-wise 17.5%, course-wise 20%. FourthWales-wise 23%, course-wise 22%.

These results were satisfactory for many purposes, but still the expenseof using formic acid was a factor to be resolved.

Example 4 For this reason, acetic ac-id was similarly treated withsulphuric acid, using a commercial solution containing 56% acetic acid,and preparing a treating solution of 50% of such acid and 50% ofsulphuric acid (120 Baume).

Swatches of the same material were treated with this solution forminutes at '150 F. Then the former procedure of rinsing, neutralizing,drying and observing was carried out.

The results obtained showed the following shrinkage:

Wales-wise 22%, course-wise 22% This proved that acetic acid could besubstituted for forrnic acid and that the shrinking effects of both wereenhanced by the presence of sulphuric acid. The shrunken fabric,especially where the shrinkage was 20% or more, had a beautiful hand and-a superior appearance.

Example 5 The above examples were carried out in small containers andu-pon small swatches of the goods. It was therefore propose-d to treat 5yards of material (simplex knitted 40 denier nylon) in a laboratory tubof larger volume capacity.

IFor this purpose, 30 liters of the solution used in Example 4 Wereprepared. The sample of cloth was loaded in -t-he tub and it was treatedfor 30 m-inutes at 160 F. The fabric was then rinsed and neutralizedwith sodium bi-carbonate solution. It was dried in a commerci-a1 type offrame and sueded. Then it was dyed a shade of dark ivory and tinished,suitable for use in gloves.

A shrinkage of 35%, both wales-wise and course-wise, was obtained. Abeautiful, heavy cloth resulted.

Various experiments were continued with various qualities of cloth,including mixtures of nylon with Arnel, Arnel and viscose, cotton andnylon, Arnel Iand silk, Amel and Bemberg, etc. While performing theseexperiments, which in the majority of cases gave satisfactory results,it was noted that the commercial acetic acid (56%) was quite oftencontaminated by metals, producing a reddish coloration in the treatingsolution which consequently left the treated cloth not in a condition tobe dyed white or pastel shades without a further bleaching. It was thendecided to substitute it with pure, glacial acct-ic acid. Of course allprevious formulas had to be ladjusted With the new concentration of acidaccordingly.

Hundreds of experiments were performed with various concentrations ofthe acids and at various tempe-ratures and it was found from them thatthe best formula for the majority of fabrics containing only nylon`fibers, was 50% sulphuric acid (20 Baume), 31% glacial acetic acid andy19% water. Time of treatment was 41/2 hour and temperature of solutionwas '160 F. However, experiments performed inthe plant, with opencontainers proved that the acetic lacid at 160 F. produced so strongfumes, that it was almost impossible for the operators to work underthese conditions. Therefore a new series of experiments was made todevelop a formula for a treating solution which would give the sameresults at room temperatures.

The concentrations of the acid treating solutions used were increasedand many variations of them tried, in order to determine the bestpossible combinations.

The results obtained by these experiments are represented in the graphsof the accompanying drawings, in which:

FIG. 1 is a chart, plotting the shrinkages obtained by the procedure ofExample 4, above, upon (A) knitted 40 d enier nylon tricot and (B) 40denier nylon 30 `gauge slrnplex, in totals of percentages (that isshrinkage waleswise plus shrinkage course-wise) with a constant timeperiod of treatment, of 30 minutes, and at a constant temperature of 150F., against varying percentages of sulphurrc acid (20 Baum) and aceticacid (56%) in the treating solutions used.

FIG. 2 is a chart, plotting the shrinkages obtained from (A) knitted 40denier nylon tricot and (B) 40 denier nylon 30 gauge simplex inpercentages (wales-wise, course- Wise and wales-wise plus course-wise)with a constant time period of treatment of 30 minutes and a constanttemperature of 78 F., against varying percentages of sulphuric acid (20Baume) and acetic acid (56%) in the treating solutions used.

FIG. 3 is a chart plotting the shrinkages obtained (upon the sarnematerials as in FIG. 2) with a constant time period of treatment of 30minutes and at a constant temperature of 80 F. (wales-wise, course-wiseand waleswise plus course-wise) against various concentrations ofsulphuric acid =(20 Baume) and of acetic acid, as glacial acetic acid inthe treating solutions used.

FIG. 4 is a chart plotting the shrinkages obtained using the samematerials with a constant time period of treatment of 3 minutes and aconstant temperature of 80 F. (wales-wise, course-wise and wales-wiseplus course-wise) with mixtures of various concentrations of sulphuricacid (20 Baume) and of acetic acid, as glacial acetic acid (100%) in thetreating solutions used.

rpossible for commercial production and operation.

From these graphs of the results obtained, it was concluded that thebest combinations for the shrinking of 40 denier nylon treated in theseexamples may be taken -as 48% sulphuric acid (20 Baurn) and 42% glacialacetic acid (100%) and 10% of water.

Further experimentation was made to reduce the time of treatment, so asto make the process as practical as It was found, as can be derived fromthe accompanying charts, that a treating solution of the above formulacan also be used in a continuous machine, where the cloth is immersed inthe liquor for 3 minutes, or for even less, namely 11/2 minutes, orless, as well as in the -vat or tub for 30 minutes, at lower acidconcentrations.

Thus, through experiment-ation, a swelling and shrinking process fornylon and other fibers has been attained, which is commercially possibleand commercially satisfactory, as demonstrated from the variousexperiments and pilot plant operations which have been performed asdescribed above. It was started with the use of formic acid alone athigh temperatures for 30 minutes. Then a combination with a mineral acidgave the desired results and also lowered the cost. The possibility ofworking it out at room temperature made it commercially feasible and thereduction of time to about a minute made it possible as a continuousprocess and consequently a very economical one.

This process is useful for many purposes:

First, by swelling synthetic bers in a knitted or woven fabric, thetexture of such treated fabric will become tighter and, therefore,improve the quality and the weight per square yard, substantially.

Second, it makes the yarn dull, giving the fabric a better appearance.

Third, in some cases, undesirable stretch has been completelyeliminated.

Fourth, it has .been shown that cloth, treated as described above, hasits substantivity toward dyestuffs increased by 25% and more.

Fifth, it has been found possible, by increasing the concentrations ofthe acid components of the above developed formula, to control thedegrees of stiffness of various fabrics, such as with a 70 denier nylonsimplex knitted fabric, in which a leather-like appearance was obtained.

`Pursuant to the results obtained by combining acetic acid, eithercommercial (56%) or glacial (100%) with sulphuric acid (20 Baum) in t-hetreating solution, parallel experiments were conducted with treatingsolutions containing other combinations, `additions or substitutions oftheir components. The results t-hus obtained are given vin theaccompanying drawings, in which:

FIG. 5 is a chart plotting the shrinking results obtained, at a constanttemperature of 80 F. in a constant time period of 3 minutes, withsolutions containing from 20% to 40% of formic acid (90%) plus from 30%to 50% of sulphuric acid Baume), upon (A) 40 denier nylon tricot and (B)40 denier nylon 30 gauge simplex.

FIG. y6 is a chart plotting the shrinking results obtained,

`upon the same goods as in FIG. 5 at a constant temper- .3. minutes,with a treating solution containing in each instance 20% sulphuric acid(20 Baume) plus from 10% to 30% glacial acetic acid (100%) and from 10%to `30% n of hydrochloric acid (20,o Baume).

`FIG. 8 isa chart, plotting the shrinkage upon the same goods as in FIG.5, obtained at a constant temperature of '80 F., in a constant timeperiod of` 3 minutes, wit-h a .treating solution containing a" constantconcentration of `20% glacial acetic acid (100%) and constant concentra-8 tion of 30% sulphuric acid (20 Baume) plus additions of hydrochloricacid (32%) of varying amounts from 14% to 20%.

From these experimentations and from the results obtained by carryingthem out, it has been demonstrated that -by the addition of sulphuricacid or hydrochloric acid to organic acid concentrations, the treatingsolution markedly increases its shrinking action and the degree ofshrinkage obtained in the resulting product.

It is also known that the inorganic or mineral acids, sulphuric andhydrochloric, While reactive separately as solvent reagents upon thesynthetic filaments and fabrics, etc., rnade from them, may be combinedand used, without any of the organic acid solvent reagents or acidicgelatinizing reagents and give effective shrinking action and results.

It is further shown that a solution containing a given concentration ofsulphuric acid (20 Baume) may be increased in its shrinking power andeffects by additions of both glacial acetic acid (100%) and hydrochloricacid (32%) in varying amounts.

It is also shown that treating solutions containing a constantconcentration (20%) of glacial acetic acid (100%) and of 30% sulphuricacid (20 Baume) may be increased in their shrinking functions andeffects by the successive additions of 14% to 20% of hydrochloric acid(32%) thereto.

It is also observed that, while shrinkage of the materials treated maybe effected with the acid solvent solution organic or inorganic, alone,or by the gelatinizing or `swelling reagent solution, alone, the use ofmixtures of the solvent reagent and of the gelatinizing or swellingreagent, in various combinations and proportions, imparts an addition tothe shrinkage effects and improved qualities of hand, texture and finishto the product obtained.

While the inorganic acids, sulphuric and hydrochloric, are active assolvent reagents toward the synthetic filaments and goods made of them,as above pointed out and demonstrated, they present the additionalfunction of activating the solvent reagents and/or gelatinizing reagentsin the treating solutions when added thereto. This is thought to be inpart attributable to the fact of their being much Vstronger acids thanthe orangic acids and characterized by presenting and providing greatlylowered ypH Values, accordingly, e.g., to below 1, to 0, and even tobelow 0, as 1, 2, etc. 'This has been mentioned above, but isdemonstrated by the following table of potentiometrically determined andrecorded values of pH of some of the treating solutions, containingvarious `combinations of organic acid solvent reagents, organic acidgelatinizing reagents, per se and in admixt-ure, and of sulphuric arcidand hydrochloric acid, per se and inadmixture, in various concentrationswith the others:

lritriic .Aejc sulahric ci c1 c1 56% (20o Water pH Baume) PercentPercent Percent Percent 9 Sulphuric acid of a concentration of 35.4%H2804 gives a pH value of --1.9.

Acetic Sulphuric Temper- Acid, Acid, 20 Water ature, pH Glacial, Baum F.Value Percent Percent Percent Without going into the theory ofionization, potentials or pH values, generally, it may be said that forthe purposes of the present invention the negative pH Values as thusindicated constitute a reverse acid capacity of the system in which theyare thus found and determined. To test this aspect of the case,applicant prepared 150 cc. of a solution of 40% formic acid (90% 50%sulphuric acid (20 Baume) and 10% of water. This solution, at 80 F., hada pH value of '-.3. Upon successive dilutions of this solution with cc.of distilled water and making corresponding determinations of the pHvalue of each resulting solution, the pH values were, respectively, .3,.3, -.3; .2, .2, .2; -.1, .1, .1, --.1; 0, 0,: -l-O.1.

In general, therefore, it may be followed as an underlying principle ofthe invention to control the solvent reagent and/ or the gelatinizingreagent in the treating solution used, in terms of its concentration itstemperature and the time period of its effective action upon the goodsand consequent function of creating and developing feltingcharacteristics and actions upon the surfaces of the lilaments or goodsunder treatment and also to activate or catalyze such characteristics,functions, actions and results, by lowering the pH value of the solutionby means of strong inorganic acids as sulphuric and hydrochloric acids.These acids may be said to be eifective themselves, to activate orcatalyze their solvent actions upon the goods in these respects, undersuitably shanply regulated conditions.

It may be pointed out that in the above described examples of theinvention the proportions of the several components of the treatingsolutions are given in the percentages of each, by volume (as one wouldnaturally measure them out in the laboratory, with a graduate) and notby weight. The water component, therefore, having a density or specificgravity of 1, will be present in a somewhat lesser proportion orpercentage, if considered in terms of proportions or percentages byweight, than when as thus given by volumefor most of the othercomponents to be added thereto have a density or specific gravity whichis greater than 1.I For example, if a solution were prepared from 75 cc.of Water (75% by volume) and 25 cc. of hydrochloric acid (25% by volume)having a specific gravity of 1.2, the resulting solution would have avolume of 100 cc. and contain 30 (25 1.2) grams of the hydrochloric acidcomponent to 75 grams of water and hence weigh about 105 grams.

The iigures above given, therefore, are subject to this slightcorrection, if they are to be considered in terms of relativeproportions or percentages, by Weight.

While the method of the invention has been described as being carriedout through the several steps and stages of procedure continuously, soas to effect the ultimate degree of the felting and shrinking functionsof the solutions upon the goods or materials treated, it is to beunderstood that various modiiications may be made in such operationswithout departing from the invention, as described and claimed. Thus,the goods or materials may be treated with the solution and thenneutralized, and/or dried, and/or washed, without permitting felting orshrinking, as by intermediate or concurrent simple retention orpositively tensioning the same to arrest such felting or shrinkingaction. Subsequently, such stage product may be relaxed and manipulatedto permit or develop the felting and shrinking to take place and thusimpart their elects and results to the treated goods or materials, ofthe kind and degree desired.

The shrinking solutions can be used, and We are using them, over andover again; occasionally it is desirable to clarify and/ or to filtersuch solutions in order to eliminate small particles and light colorwhich could have accumulated during the various treatments.

I claim:

The method of effecting the characteristics of inherent felting upon andthe consequent shrinking of uniformly chemically and physicallyresistant, smooth surfaced, synthetic lbers of nylon, in knitted andwoven fabricated textile goods made of them, which comprises the stepsof subjecting said textile goods to an aqueous solution of the groupconsisting of (A) a mixture of 46% to 50% glacial acetic acid of 100%and 45% to 50% sulphuric acid of 20 Baume; (B) a mixture of 40% formicacid of and 30% to 50% sulphuric acid of 20 Baume; (C) `a mixture of 30%hydrochloric acid of 20 Baum and 30% to 40% sulphuric acid of 20 Baume;(D) a mixture of 10% glacial acetic acid of 100% and 25% to 30%hydrochloric acid of 20 Baum; and (E) a mixture of 20% glacial aceticacid of 100%, 30% sulphuric acid of 20 -Baum and 18% to 20% hydrochloric-acid of 20 Baum, said percentages being by volume, at room temperatureand for a period of time of approximately 3 minutes to regulate, developand determine the degree of felting and shrinking to a total addedshrinkage, in length and width, of over 40%, and arresting the action ofthe solution thereon by removing the active agent from the goods.

References Cited by the Examiner UNITED STATES PATENTS 2,006,540 7/ 1935Dreyfuss et al. 8-131 2,730,478 1/ 1956 Morgan. 2,730,479 1/1956 Gibson.2,774,126 12/1956 Secrist. 2,869,974 1/1959 Adams 8-130.1 2,897,042 7/1959 Heiks. 2,900,669 8/1959 Booth 8--131 2,904,840 9/1959 Hochreuter.2,981,978 5/1961 Grilling. 3,014,830 12/1961 Stallard et al. 3,083,0713/ 1963 Wishman 8-130.1

FOREIGN PATENTS 553,442 5 1943 Great Britain. 562,555 7/ 1944 GreatBritain. 748,964 5/1956 Great Britain.

NORMAN G. TORCHIN, Primary Examiner.

WILLIAM B. KNIGHT, MORRIS O. WOLK, Examiners.

